A method for detecting full-load feeder network of energy-saving and emission-reduction dual-use shore power system

Abstract

The present invention relates to the field of electric power system power feed network, specifically, a method for full-load feed network detection of a dual-use shore power system for energy conservation and emission reduction, which realizes that when the shore power supply performs load detection, the tested electric energy is fed back to the power grid for energy recovery. The method includes: using a phase-locked loop method to synchronize the output voltage of the shore power supply with the grid voltage; using a VSG control strategy to switch the shore power supply working mode; using a frequency conversion device to feed back the electric energy drawn from the shore power box to the shore power supply side; adjusting the power factor to simulate the load of the shore power system for load testing; and forming a dual-use structure of shore power supply self-detection and shore power supply load detection. This method meets the requirements for regular inspection of the shore power supply, and at the same time feeds the tested electric energy back to the power grid, thereby achieving energy conservation and emission reduction.

Description

Technical Field

[0001] The present invention relates to the field of electric power system power feed network, in particular to a method for detecting full-load feed network of a dual-use shore power system for energy saving and emission reduction. Background Art

[0002] Due to the large number of ships operating in the port, the large amount of pollutants emitted by their diesel generators during operation has caused the air quality in coastal areas to deteriorate. At the same time, the country has also promulgated corresponding shore power implementation plans to encourage and promote the construction and use of shore power at terminals.

[0003] Since shore power supply testing is relatively frequent, the existing testing method is to use actual ships or large resistive and inductive load combinations to adjust the corresponding loads according to the testing needs. However, these testing devices cannot perform stepless adjustment of the power factor during the testing process and cannot simulate the load conditions of various types of ships. At the same time, a large amount of electrical energy is dissipated in the form of heat during testing, resulting in a huge waste of resources. Currently, about 90% of electricity comes from thermal power generation, which leads to large emissions of CO2 and other pollutants. At the same time, if the terminal is equipped with special testing equipment for the shore power system, the investment will be too large and not practical. Frequent rental of load equipment is not realistic. At present, the placement of shore-based power supply systems is mostly fixed on land, which brings many inconveniences when supplying power and repairing ships at port.

[0004] According to the "JTS 155-1-2019 Technical Specification for Testing of Dock Shore Power Facilities," shore power should be tested every 12 months of normal use or after three months of inactivity before use again. Load testing of shore power is typically performed on actual vessels or using large dry-type resistance and inductance testers, which wastes significant energy and harms the environment. Summary of the Invention

[0005] The present invention provides a method for full-load feeder detection of a dual-use shore power system for energy conservation and emission reduction, so as to solve the problem that the existing shore power supply is subjected to load testing and is tested using actual ships or large dry-type resistance and inductance boxes, which wastes a lot of energy and damages the environment. At the same time, the electric energy drawn from the shore power box is fed back to the shore power supply side through a frequency conversion device, forming an energy closed loop, which saves both costs and energy, and reduces carbon emissions and environmental pollution. At the same time, the dual-use shore power supply can both adjust the power factor of the power grid and improve system stability.

[0006] A method for detecting a fully loaded feeder network of a dual-use shore power system for energy saving and emission reduction includes the following steps:

[0007] Step 1: Use a phase-locked loop (PLL) to synchronize the shore power output voltage with the grid voltage.

[0008] Step 2: When the shore power supply performs load detection, the voltage-controlled VSG control strategy is used to switch the shore power supply operation mode to the grid feeding state;

[0009] Step 3: The power drawn from the shore power box is fed back to the shore power supply side through the frequency conversion device (rectifier, inverter), so that the energy forms a closed loop;

[0010] Step 4: Simulate the load of the shore power system by adjusting the power factor;

[0011] Step 5: Perform load detection on shore power supply;

[0012] Step 6: When the shore power supply performs self-test, skip directly from step 1 to step 7;

[0013] Step 7: Use the voltage-controlled VSG control strategy to switch the shore power supply working mode to the power supply state;

[0014] Step 8: Perform a self-test on the shore power supply.

[0015] A further improvement of the present invention is that in step 1, θ PLL Represents the grid output voltage V adc The phase difference between the output voltage of the phase-locked loop (PLL) and V adc With an angle equal to θ PLL Perform Park transform and its inverse transform to make the grid output voltage V adc Synchronizes with shore power output voltage.

[0016] As a further improvement of the present invention, in step 2 and step 7, a voltage-controlled VSG control strategy is adopted to achieve grid-connected, off-grid, and seamless switching between the two modes, providing voltage and frequency support for the microgrid system.

[0017] A further improvement of the present invention is that in step 3, since the grid output voltage V adc It is synchronized with the shore power output voltage, so it can feed the grid and feed the power drawn from the shore power box back to the shore power side.

[0018] A further improvement of the present invention is that in step 4, the phase relationship between voltage and current is adjusted through SVPWM, that is, the power factor is adjusted, so as to achieve the purpose of simulating the shore power system load and further complete the full load detection of the shore power system.

[0019] According to a further improvement of the present invention, in step five and step eight, the shore power self-detection and the shore power load detection form a dual-use shore power system full-load feeder detection network.

[0020] Beneficial effects of the present invention:

[0021] 1. The present invention draws electric energy from the shore power box and feeds it back to the shore power supply side through the frequency conversion device, so that a closed loop is formed and energy is fed back to the power grid, which is beneficial to reduce environmental pollution and reduce testing costs.

[0022] 2. The present invention simulates the load of the shore power system by adjusting the power factor, which is used to test the load capacity of the shore power supply, thereby reducing energy consumption and environmental pollution.

[0023] 3. The present invention has low testing cost, which provides favorable conditions for studying the power consumption status control mode of the shore power supply system.

[0024] 4. The present invention has low testing cost, thus providing conditions for ensuring the reliable operation of the shore power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a system block diagram of the present invention.

[0026] Figure 2 Schematic diagram of the doubly-fed shore power supply system in the present invention.

[0027] Figure 3 Schematic diagram of the VSG control strategy of the shore power supply system in the present invention.

[0028] Figure 4 Schematic diagram of the power consumption status control mode of the shore power supply system in the present invention.

[0029] Figure 5 This is a schematic diagram of the shore power supply load detection state structure in the present invention.

[0030] Figure 6 This is a schematic diagram of the shore power supply self-detection state structure in the present invention.

[0031] Figure 7 Schematic diagram of the full-load feeder detection network of the dual-use shore power system in the present invention.

[0032] Figure 8 This is a hardware topology diagram of the doubly-fed power system in the present invention. DETAILED DESCRIPTION

[0033] In order to deepen the understanding of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The embodiments are only used to explain the present invention and do not limit the scope of protection of the present invention.

[0034] Example: Figure 1 As shown, a full-load feeder detection system for a dual-use shore power system for energy saving and emission reduction is provided. The method uses a simulated load with a changed power factor to detect the shore power load and combines load detection and self-detection into a dual-use system, including the following steps:

[0035] The phase-locked loop method is used to synchronize the output voltage of the shore power supply with the grid voltage, and the voltage-controlled VSG control strategy is used to switch the shore power supply working mode to the grid feeding state and the power supply state, and the shore power supply in this state is subjected to full load detection and self-detection respectively.

[0036] First, the grid output voltage V adc With an angle equal to θ PLL Perform Park transformation and its inverse transformation to make the grid output voltage V adc Synchronize with the shore power output voltage via the phase-locked loop (PLL), where θ PLL Represents the grid output voltage V adc The phase difference between the output voltage of the phase-locked loop (PLL) and the output voltage of the phase-locked loop (PLL) enables the power feed operation in the subsequent shore power load detection state of this experiment.

[0037] Then, the voltage-controlled VSG control strategy is used to switch the shore power supply working mode according to different working purposes, such as Figure 2 As shown, the left side is the shore power supply, the upper right side is the shore power supply system, and the lower right side is the ship system. Through the VSG control strategy, the shore power supply works in the load detection (grid feeding) state, so that the shore power supply feeds electric energy back to the shore power supply system, and completes the simulation load, load detection and other contents in the process; or through the VSG control strategy, the shore power supply works in the power supply state, so that the shore power supply normally supplies power to the ship power system, and completes the self-detection and other contents in the process. Figure 4 As shown, the grid feeding state and the power supply state can be switched between each other by inputting grid feeding instructions and power supply instructions.

[0038] At the same time, the grid feeding state and the power supply state can be switched between each other by inputting grid feeding instructions and power supply instructions. Figure 3 As shown, the shore power system's power usage states are power supply, grid feed, shutdown, and standby. When the shore power system is performing load testing, it is in the shutdown state. Startup commands, power supply commands, and grid feed commands are sequentially input to the shore power system, and the VSG control strategy switches the shore power system's operating mode from shutdown, standby, power supply, and finally to grid feed. When the shore power system is performing self-testing, it is in the grid feed state. Power commands are input to the shore power system, and the VSG control strategy switches the shore power system's operating mode from grid feed to power supply.

[0039] When the shore power supply is performing load detection, the shore power supply is in shutdown state. The startup command, power command, and grid feed command are input to the shore power supply system in sequence. The shore power supply working mode is switched from shutdown state, standby state, power supply state to grid feed state through the VSG control strategy. Figure 5As shown, the output end of the frequency converter is directly connected to the shore power supply side A instead of connecting it to the ship load B. That is, the power is drawn from the shore power box and fed back to the shore power supply side through the frequency converter, so that the energy forms a closed loop.

[0040] Since the grid output voltage V adc It is synchronized with the shore power output voltage, so it is possible to perform power feeding operation during the shore power load detection state in this experiment, that is, feeding the power drawn from the shore power box back to the shore power side.

[0041] Then, the phase relationship between voltage and current is adjusted through SVPWM, that is, the power factor is adjusted, so as to achieve the purpose of simulating the shore power system load and complete the full load detection of the shore power system.

[0042] When the shore power supply performs self-test, the shore power supply is in the grid feeding state, and the power supply instruction is input to the shore power supply system, and the shore power supply working mode is switched from the grid feeding state to the power supply state through the VSG control strategy. Figure 6 As shown, the output end of the frequency converter is connected to the ship load, so that the shore power supply enters the power supply mode, and on this basis, a self-detection circuit AB is added to perform self-detection of the shore power supply.

[0043] At the same time, the VSG control strategy in the present invention adopts a voltage-controlled VSG control strategy. The voltage-controlled VSG control strategy can achieve grid-connected, off-grid, and seamless switching between the two modes, and provide voltage and frequency support for the microgrid system.

[0044] Finally, the shore power self-detection and shore power load detection form a dual-use shore power system full load feeder detection network, such as Figure 7 As shown, two energy channels are formed between node A and node B via the frequency conversion device, that is, a dual-use system structure.

[0045] Figure 8 This is the hardware topology diagram of the doubly-fed power system in the present invention. As shown in the figure, its main structure consists of two groups of three-phase bridge arms composed of IGBT bridges, which enables the system to complete the current conversion process (AC-DC-AC) of bidirectional rectification and inversion. In this process, the voltage and frequency can be adjusted to better complete the subsequent grid connection or feeding work; at the same time, filtering devices are added at the input and output ends to filter the input and output currents and voltages, improve the power quality, and meet the current and voltage requirements of the grid connection and feeding.

[0046] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for detecting full-load feeder network of a dual-use shore power system for energy saving and emission reduction, characterized in that: The following steps are involved: Step 1: Use a phase-locked loop method to synchronize the output voltage of the shore power supply with the grid voltage; Step 2: Use the voltage-controlled VSG control strategy to switch to shore power supply working mode; Step 3: When the shore power supply is subjected to load detection, the voltage-controlled VSG control strategy is used to switch the shore power supply operating mode to the load detection state; Step 4: Use a frequency converter to feed the power drawn from the shore power box back to the shore power supply side; Step 5: Simulate the load of the shore power system by adjusting the power factor; Step 6: Perform load test on shore power supply; Step 7: When the shore power supply is self-tested, go directly from step 2 to step 7, and use the voltage-controlled VSG control strategy to switch the shore power supply to the power supply state; Step 8: Perform a self-test on the shore power supply; Step 9: Shore power self-test and shore power load test form a dual-use shore power system full-load feeder test network; In step 1, the grid output voltage Angle equal to Perform Park transformation and its inverse transformation to make the grid output voltage Phase-locked loop Shore power output voltage synchronization, where Represents the grid output voltage Phase-locked loop The phase difference between the output voltages.

2. The method for detecting full-load feeder network of a dual-use shore power system for energy saving and emission reduction according to claim 1, characterized in that: In the step 2, the transformation modes of the shore power supply system during operation mainly include power supply state, grid feed state, shutdown state and standby state, and the shore power supply system power consumption state control mode.

3. The method for detecting full-load feeder network of a dual-use shore power system for energy saving and emission reduction according to claim 1, characterized in that: In step 4, the frequency conversion device is composed of a rectifier and an inverter, and the output end of the frequency conversion device is directly connected to the power grid, and the electric energy drawn from the shore power box is fed back to the shore power supply side.

4. The method for detecting full-load feeder network of a dual-use shore power system for energy saving and emission reduction according to claim 1, characterized in that: In the step five, the phase relationship between the voltage and the current is adjusted by SVPWM.

5. The method for detecting full-load feeder network of a dual-use shore power system for energy saving and emission reduction according to claim 1, characterized in that: In step nine, the shore power self-detection and the shore power load detection form a dual-use shore power system full-load feeder detection network.

Images